1. Field of the Invention
This invention relates to a coloring apparatus and process, such as a dyeing or printing process for a leather. More particularly, the present invention relates to a leather coloring process, and a leather coloring apparatus, that enables highly minute image formation on leather by a simple and high-speed operation.
In addition to the above, the present invention also relates to a coloring treatment process attaining a simplification for various finishing processes, and a coloring treatment apparatus thereof, as well as also relating to a leather produced after such leather coloring and a leather product obtained by processing the leather.
2. Related Background Art
Leathers are commonly produced according to the following processes. First, raw hide or skin obtained by skinning animals is subjected to a preliminary, beamhouse process comprised of soaking, fleshing, unhairing, liming, splitting, scudding, washing, reliming, deliming and bating subsequently to a tanning process to carry out tanning by the use of a tanning agent of various types such as chromium compounds and vegetable tannin in order to impart softness and thermal resistance to the hide or skin, and thereafter a dyeing and fatliquoring process comprised of neutralizing, dyeing and fatliquoring (or stuffing), finally followed by a finishing process comprised of sammying, setting-out, drying, conditioning, staking, stretch drying, trimming, grain correcting, coating, and measuring, where durability, fastness and the like are improved. Having been subjected to these processes, leather products are obtained as final products.
Leather products are utilized in a great variety of fields, making the most of the handle (or hand) inherent in leathers. For example, they are utilized in a vast range of footware such as shoes, clothes, personal ornaments such as gloves and belts, traveling goods such as bags, trunks (or suitcases) and purses, industrial parts such as belts and gaskets, and furniture such as chairs and automobile seat sheets, as well as horse gear, musical instruments, kendo (Japanese style fencing) goods, and so forth. In such respective fields, hide or skin of various animals and various tanning methods are used. For such uses, hitherto in addition to dyeing the hide or skin in specified color in whole, at a finishing step, varieties in surface shapes as in embossing leather and suede are provided to make these types of leather products abundant and to exhibit a high-grade quality.
Under such circumstances, the coloring on leather by conventional dyeing or coating is carried out using dyes or pigments. Almost all of these coloring materials are those employed from dyes or pigments hitherto used in the dyeing of textiles, and coloring processes suitably selected according to the kind of raw hide or skin, the manner of tanning and the type of use. For example, there are processes such as battick dyeing, dip dyeing and textile printing.
Under actual circumstances, however, since the leather has various properties according to its kind, actual operation still largely depends on experience. Even when the leather is colored in monochrome, the coloring on some kinds of leathers takes a long time for its operation, requires complicated operation steps, or makes it necessary to repeat the same step many times. Hence, it has been very difficult to mass-produce dyed products of the same design or to dye leather to form highly minute images or multi-color images.
Meanwhile, the surface of leather, in particular, what is called the grain side of natural leather has irregularities or large concavities because of follicle mouths (pores of the skin) or various wrinkles originally present in raw hide or skin. If the leather is dyed in that state, dyeing agents may conspicuously gather to that part to cause highly deep-colored portions. Also when the leather is dyed after it has been smoothened to eliminate irregularities or large concavities in treating steps, it is difficult to perfectly smooth the surface, so that the leather may be non-uniformly colored or non-colored at the first operation. To overcome such disadvantages, it is often necessary to reform many steps or to repeat the operation of dyeing and rinsing several times. Namely, it is difficult to obtain the desired state of dyeing and the desired color tones. As a result, it tends to provide only leather products with varied color tones.
On the contrary, in the general trends of wanting to have products with a sense of high grade in everyday living goods and ornaments, leather products can also more highly enjoy the sense of high grade inherent in leather if products with highly minute images formed on the surface can be readily obtained, and also it is possible to intend an application of leather products in a wider range if it becomes possible to form multi-color images or to carry out partial printing on leathers with ease.
However, as previously stated, the hitherto known dyeing and coating processes require a large number of steps and hence take a long time for their operation, in order to maintain color density and fastness. Moreover, leathers are hitherto mostly dyed in monochrome, and hence, in order to represent multi-color images on leather, it has been necessary to stick or stitch sheet by sheet a plurality of leathers dyed in different colors. There has been also a limit in number even if some kinds of colors can be represented on the same leather. At any event, the manner of dyeing or coating may often differ for each color and also the dyeing or coating has been manually operated in many instances, so that the experience can of the one performing the dyeing or coating process is a great factor which shows in the final product. Thus, in the past, the dyeing on leathers has been mostly supported by know-how, and hence it has been difficult to automate the operation, resulting in a high cost.
Thus, it will be complicated in processes and high in cost to express minute image and multi-color image and further to make a partial image formation only by improving conventional dyeing methods.